Re: [PATCH] slub: make sysfs file removal asynchronous

From: Steven Rostedt
Date: Tue Jun 20 2017 - 18:22:22 EST

On Tue, 20 Jun 2017 18:00:11 -0400
Tejun Heo <tj@xxxxxxxxxx> wrote:

> > > Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> > > Reported-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> > > Tested-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> > > Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()")
> >
> > Do you think we should add cc:stable [4.11+]?
> I think we'd risk more by backporting it through -stable than keeping
> the bug there. The bug is very difficult to hit.

Famous last words.

> Writing to a slub
> sysfs file has to race against kmem_cache destruction and AFAICS all
> slub sysfs files are for debugging.

It's not that big of a change. It's simply moving the work to a work
queue. I've done bigger changes than this and backported it to stable
for similar reasons.

All it takes is for it to be hit once in a billion, and that billionth
time could be critical.

-- Steve